Monoclonal antibodies against Salmonella porins : generation and characterization

Monoclonal antibodies (mAbs) were generated against porins, one of the major outer membrane proteins of Salmonella typhi. Six clones, designated MP1, MP2, MP3 (IgG2ak), MPN4, MPN6 (IgG1k) and MPN5 (IgG2bk) were characterized by enzyme immunoassay (ELISA) for their reactivity to porins from S. typhi, Salmonella paratyphi A, S. paratyphi B, S. paratyphi C, Salmonella choleraesuis, Salmonella enteritidis, Salmonella krefeld, Salmonella panama, Salmonella typhimurium, Escherichia coli B, Shigella flexneri 1b and Pseudomonas aeruginosa. All the clones positive for S. typhi porins showed varying reactivity towards several Salmonella species. However, none of them was positive for porins from other Gram-negative bacteria or for lipopolysaccharide (LPS). The affinity constant of these mAbs, except MPN4, was found to be in the higher range. Dot ELISA revealed that the mAbs recognized porins only in their native form. The results of inhibition ELISA using horseradish peroxidase (HRP)-conjugated MP1 suggest that the clones MP1, MP2, MP3, MPN5 and MPN6 secreted antibodies to identical epitope(s) of a 36-kDa peptide and MPN4 to a different epitope of a 35-kDa peptide. The possible applications of these mAbs were discussed.